The present invention relates to a transflective liquid crystal display device, and more particularly to a technique which is effectively applicable to an IPS (In Plane Switching)-type transflective liquid crystal display device.
A transflective liquid crystal display device which includes a transmissive portion and a reflective portion within one sub pixel has been used as a display of a portable equipment.
On the other hand, as a liquid crystal display device, there has been known an IPS-type liquid crystal display device. This IPS-type liquid crystal display device forms pixel electrodes (PIX) and counter electrodes (COM) on the same substrate and controls contrast by rotating liquid crystal in a plane of the substrate by applying an electric field between the pixel electrodes (PIX) and the counter electrodes (COM) Accordingly, this IPS-type liquid crystal display device possesses a feature that when a viewer observes a screen from an oblique position, intensity or contrast of a display image is not inverted. To effectively make use of such a feature, for example, patent document 1 (JP-A-2003-344837), patent document 2 (JP-A-2005-338256), patent document 3 (Japanese Patent Application 2005-331227) and the like propose transflective liquid crystal display devices which are formed using the IPS-type liquid crystal display device.
As a method for forming the transflective liquid crystal display device using the IPS-type liquid crystal display device, in patent document 1, a half-wave plate is formed on a transmissive region and a reflective region, the transmissive region is driven by a lateral electric field, and the reflective region is driven by a vertical electric field. On the other hand, in patent document 2, a half-wave plate is formed only on a reflective region, and both of a transmissive region and the reflective region are driven by a lateral electric field.